The Fifth Petition: And forgive us our trespasses as we forgive those who trespass against us. What does this mean?

We pray in this petition that our Father in heaven would not look at our sins, or deny our prayer because of them. We are neither worthy of the things for which we pray, nor have we deserved them, but we ask that He would give them all to us by grace, for we daily sin much and surely deserve nothing but punishment. So we too will sincerely forgive and gladly do good to those who sin against us.